CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 2, March/April 2022 64 AFRICA findings, which were uniform with each category of left atrial size, above or below 60 mm.13 According to Ad et al., left atrial size was a predictor only of success at six months, otherwise, similar to our study, the left atrial size had no influence on success rates earlier or later than six months.11 This can be explained again on the basis of completeness of transmural ablation lines to form physical electrical barriers, hence compartmentalising the atrium and leaving only one corridor to direct the flow of electrical current. Therefore, the maze principle of remaining with only one electrical pathway is what is important for any left atrial size. Only three patients had atrial flutter rhythm after left atrial ablation in our study, two in the first three months and one between six and nine months. The 5.9% atrial flutter rate in our study is comparable to the 10% found by Chavez et al.,9 which used bi-atrial ablation. This suggests that the hypothesis by Cox et al., that there is a risk of converting atrial fibrillation to atrial flutter, is a reality and not a myth.4 The long-term rhythm status of a patient was determined by the rhythm status of the patient recorded in the three- to six-month period. There was a 100% probability that patients remained in sinus rhythm provided that they were in sinus rhythm between three and six months. Similarly, there was a 93% probability that patients would remain in atrial fibrillation for more than two years if they were in atrial fibrillation in the three- to six-month period. This was not influenced by the use or non-use of anti-arrhythmic medication. Therefore, follow up of patients can be done less frequently after the first six months post cardiac ablation. In this South African community, rheumatic MMVD was responsible for more than two-thirds of the surgical valvular heart patients complicated by atrial fibrillation. Limitations of the study As a retrospective study done at a referral hospital, it was not possible to control the variables already in the patient files. Where information was not recorded, conclusions were drawn on the basis of available data. The number of missing recordings of ECG status on patients increased over time, with fewer patient rhythm statuses from 12 months onwards. This may have affected the long-term outcomes recorded in this study. The lack of a 24-hour Holter monitor, which the studies by Ad et al. and Pecha et al. had, makes our rhythm status less comprehensive than that of other studies, although standard by definition.11,13 Rhythm monitoring was dependent on the available doctor at that time, not a dedicated, independent and blindfolded monitoring team, as used by Blackstone et al. in the USA.8 Although our study focused on the surgeon factor in ablation, it did not compare how much more time left atrial ablation adds to valvular heart surgery. Such information may have an overall influence on the mortality and morbidity rates, which were not analysed. There was no randomisation of patients into different categories, which would have assisted in comparing left atrial ablation with a different technique, such as the bi-atrial (maze) technique. Conclusions Left atrial cardiac ablation during valvular heart surgery was effective in the treatment of atrial fibrillation in patients with a good ejection fraction undergoing valve surgery. However, about 16% of patients relapsed back to atrial fibrillation after successful left atrial ablation. Atrial flutter occurred in less than 5% of patients after left atrial cardio-ablation. The patient’s rhythm status between three and six months after left atrial ablation determined his/her long-term rhythm, which was not affected by anti-arrhythmic medications. This article represents Dr D Nyamande’s mini-dissertation for the MMed Cardiothoracic Surgery degree submitted at Sefako Makgatho Health Sciences University in 2019. He acknowledges the supervisor and head of department, Prof RF Chauke and co-supervisors Dr SM Mazibuko and Dr PS Ramoroko, as well as the departments of Cardiothoracic Surgery and Cardiology and the staff at Dr George Mukhari Academic Hospital. He thanks the Sefako Makgatho Health Sciences University research and library staff, and Prof Schoeman for statistical analysis, as well as his family for support. References 1. Lip GYH. Antithrombotic therapy in AF with valvular heart disease. Eurospace 2017; 19: 1757–1758. 2. Jardine RM, Fine J, Obel IWI. A survey on the treatment of atrial fibrillation in South Africa. S Afr Med J 2014; 104(9): 623–627. 3. Nishimura RA, Otto CM, Bonow RO, Carabello BA, Erwin JP, Guyton RA, et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: executive summary. Circulation 2014; 129(23): 2440–2492. 4. Cox JL, Ad N. New surgical and catheter-based modifications of the maze procedure. Seminars Thorac Cardiovasc Surg 2000; 12(1): 68–73. 5. Ruaengsri C, Schill MR, Khiabani AJ, Schuessler RB, Melby SJ, Damiano RJ Jr. The Cox-maze IV procedure in its second decade: still the gold standard? Eur J Cardiothorac Surg 2018; 53: 19–25. 6. Li H, Lin X, Ma X. Biatrial versus isolated left atrial ablation in atrial fibrillation. Biomed Res Int 2018: 1–3. 7. Talle MA, Bonny A, Scholtz W, Chin A, Nel G, Karaye KM, et al. Status of cardiac arrhythmia services in Africa in 2018. Cardiovasc J Afr 2018; 29(2): 115–29. 8. Blackstone EH, Chang HL, Rajeswaran J, Parides MK, Ishwaran H, Li L. Biatrial maze procedure versus pulmonary vein isolation for atrial fibrillation during mitral valve surgery. J Thorac Cardiovasc Surg 2019; 157(1): 234–243. 9. Chavez EK, Colafranceschi AS, Monteiro AJ, Canale LS, Mesquita ET, Weksler C, et al. Surgical treatment of atrial fibrillation in patients with rheumatic valve disease. Braz J Cardiovasc Surg 2017; 32(3): 202–209. 10. Raman J, Ishikawa S, Storer M, Power JM. Surgical radiofrequency ablation of both atria for atrial fibrillation. J Thorac Cardiovasc Surg 2003; 126(5): 1357–1366. 11. Ad N, Holmes SD, Shuman DJ. Left-sided surgical ablation for patients with atrial fibrillation who are undergoing concomitant cardiac surgical procedures. Ann Thorac Surg 2017; 103: 58–65. 12. Van Breugel HNAM, Gelsomino S, de Vos CB, Accord RE, Tieleman RG, Lucà F, et al. Maintenance of sinus rhythm after electrical cardioversion for recurrent atrial fibrillation following mitral valve surgery with or without associated radiofrequency ablation. Int J Cardiol 2014; 175: 290–296. 13. Pecha S, Ghandili S, Hakmi S, Willems S, Reichenspurner H, Wagner FM. Predictors of long-term success after concomitant surgical ablation for atrial fibrillation. Semin Thorac Cardiovasc Surg 2017; 29(3): 294–298.
RkJQdWJsaXNoZXIy NDIzNzc=